Surface color treatment of alloys with micro-arc oxidation process

Abstract

Example embodiments include methods of treating a surface of an aluminum (Al) alloy or magnesium (Mg) with an electrolyte to obtain a surface with a coloration that is uniformly enhanced. Example embodiments also include surface-treated Al alloy or Mg alloy made by the example methods.

What is claimed is: 
     
       1. A method of treating a surface of a magnesium (Mg) alloy, comprising:
 immersing the Mg alloy into an electrolyte; and 
 applying an electric current with a current density of 0.03-0.17 A/cm 2  and a pulse frequency of 500-2,600 Hz on the Mg alloy for a time duration of 100-720 seconds, 
 wherein the Mg alloy comprises:
 8.3-9.7 weight percent of aluminum (Al); 
 0.35-1.0 weight percent of zinc (Zn); 
 0.15-0.50 weight percent of manganese (Mn); and 
 a balanced percent of Mg; 
 
 wherein the electrolyte is a mixture of 20-30 g/L silicates, 5-20 g/L phosphate, 3-6 g/L hydroxide, 5-10 g/L glycerol, 0.5-2 g/L tungstate, and 5-15 g/L titanium dioxide (TiO 2 ) nanoparticles in deionized (DI) water, and 
 wherein a color of the surface of the Mg alloy that is treated by the method is uniformly enhanced. 
 
     
     
       2. The method of  claim 1 , wherein the silicate is sodium metasilicate nonahydrate. 
     
     
       3. The method of  claim 1 , wherein the phosphate is sodium pyrophosphate decahydrate. 
     
     
       4. The method of  claim 1 , wherein the hydroxide is sodium hydroxide. 
     
     
       5. The method of  claim 1 , wherein the tungstate is sodium tungstate. 
     
     
       6. The method of  claim 1 , wherein the TiO 2  nanoparticle is rutile titanium dioxide with a particle size of 30 nm. 
     
     
       7. A surface-treated magnesium (Mg) alloy, comprising:
 a Mg alloy wherein the Mg alloy includes:
 8.3-9.7 weight percent of aluminum (Al); 
 0.35-1.0 weight percent of zinc (Zn); 
 0.15-0.50 weight percent of manganese (Mn); and 
 a balanced portion of Mg; 
 
 a Mg based ceramic layer that has a thickness of 5-40 μm and that is formed on a surface of the Mg alloy; and 
 a layer of Titanium (Ti) that is distributed in the Mg based ceramic layer, 
 wherein the Mg based ceramic layer uniformly enhances a color appearance of the surface of the Mg alloy. 
 
     
     
       8. The surface-treated magnesium (Mg) alloy of  claim 7 , wherein the surface-treated Mg alloy has a sRGB value of ( 97 ,  100 ,  106 ), ( 69 ,  71 ,  80 ), ( 104 ,  107 ,  111 ), ( 164 ,  158 ,  158 ), or ( 134 ,  132 ,  134 ). 
     
     
       9. The surface-treated magnesium (Mg) alloy of  claim 7 , wherein the surface-treated Mg alloy is made by the method of  claim 1 .